Closure means for pressurized furnaces



June 19, 1962. E. L. DAMAN CLOSURE MEANS FOR PRESSURIZED FURNACES 3 Sheets-Sheet 1 Filed Aug. 1, 1957 ERNEST L. DAMAN A'ITORNEY June 19, 1962 L, DAMAN I 3,039,407

CLOSURE MEANS FOR PRESSURIZED FURNACES A Filed Aug. 1, 1957 5 Sheets-Sheet 5 INVENTOR ERNEST I... DAMAN ATTORNEY United States Patent 9 3,039,407 CLOSURE MEANS FOR PRESSURIZED FURNACES Ernest L. Daman, Westfield, N .J., assignor to Foster Wheeler Corporation, New York, N.Y., a corporation of New York Filed Aug. 1, 1957, Ser. No. 675,774 Claims. (Cl. 110-179) This invention relates to closure means for pressurized furnaces and more particularly to a door assembly for an access opening in a pressurized furnace.

During the operation of pressurized furnaces, access is required to the interior of the furnace for cleaning and other purposes. To this end, an access opening is provided in the wall of the furnace and is sealed from the exterior thereof by a door. The pressure within the furnace is greater than that outside so that opening of the door while the furnace is in operation gives rise to a dangerous condition wherein hot products of combustion escape through the access opening. In order to overcome this condition, the prior art has disclosed numerous arrangements for injecting a fluid into the access opening and toward the interior of the furnace to restrict or repel the outward rush of combustion gases, together with means for initiating the flow of injected fluid prior to operation of the door from a closed position to an open position. In some instances, a mechanical interlock is provided between the door and a valve which controls the injection of fluid into the access opening, to prevent opening of the door unless the valve is actuated initially. Furthermore, it has been proposed to utilize an arrangement wherein the door is maintained in a closed position if the pressure in a fluid manifold associated with the door does not reach a certain value.

It is an object of the present invention to provide a novel door assembly for access openings in pressurized furnaces which insures the flow of fluid into the access opening prior to the operation of the door to an open position. v

The present invention contemplates a novel door assembly which includes a manifold for injecting fluid into the access opening. Manually operable locking means are provided for preventing operation of the door except upon the passage of fluid from the manifold to the access opening. Restraining means cooperate with the locking means to prevent operation of the latter when flow of fluid through the manifold is non-existent and permits operation of the locking means upon flow from the manifold to the access opening.

The above objects and other advantages of the present invention will appear more clearly from the following detailed description of the invention when taken in connection with the accompanying drawings in which one embodiment of the present invention is illustrated.

In the drawings:

FIG. 1 is a front elevational view of the door assembly of the present invention; a

FIG. 2 is a side view and partly in section taken along the line 2-2 of FIG. 1;

FIG. 3 is a sectional view taken along the line 33 of FIG. 1;

FIG. 4 is a sectional view of a portion of the door assembly taken along line 44 of FIG. 1;

FIG. 5 is a partly diagrammatic representation of the door assembly of FIG. 1 and more clearly discloses the control for and means for introducing fluid to the manifold of FIGS. 2 and 3; and

FIG. 6 is an enlarged view showing the detailed construction of orifice means associated with the conduit of FIG. 4.

Referring now to the drawings and more particularly to FIG. 1 thereof wherein one embodiment of the present "ice invention is illustrated, a door assembly, generally desig nated by the numeral 12, comprises a door frame 14 which is adapted for mounting on a vertical outer casing 15 (partly shown) disposed on an insulated wall 16 of a furnace (not shown). Disposed on the side of door frame 14, toward the furnace interior, is a manifold 18 (FIG. 3) which includes a pair of concentric annular members 26 and 22, and said members abut an annular plate 24, extending transversely thereof, to define a manifold chamber 26. A sleeve 27 is secured normal to plate 24 and disposed in an opening 28 of wall 16; the sleeve and opening constitute an access opening 29. The inner surface of wall 16 is lined with a sheet 30 and arranged in front of the latter are fluid conducting tubes 31. A

plurality of holes or ports 32 are drilled in plate 24 and are arranged in a circular row, preferably at equal circumferential distances. Holes 32 are provided for injecting a gaseous medium under pressure, as for example air, into access opening 29 in a direction away from door frame 14. The high pressure air is supplied to manifold chamber 26 via a connecting chamber 34 (FIG. 4) which communicates with chamber 26 through an opening 36 in annular member 22. An elbow coupling member 37 is mounted in frame 14 and communicates connecting chamber 34 with a source of high pressure air (not shown) through a conduit 38 connected thereto. The air injected into access opening 29 through ports 32 provides a fluid barrier to the flow of combustion gases to ward the door frame 14.

One end of annular member 20 extends into an opening 40 formed in frame 14. A sealing ring 41 is disposed in a recessed portion of frame 14, which encompasses the opening 40, and the ring is adapted to be engaged by a door 42 for sealing access opening 29 from the outside of the furnace. A transparent member or window 43 is provided in door 42 and is mounted in a resilient insert 44 in a recess formed in door 42. Insert 44 is engaged by a retainer member 47 which is secured to door 42 by a plurality of threaded members 48. Diametrically opposed lugs 49 are provided on and adjacent the outer edge of door 42 and each lug has an opening to accommodate a stud 50. The studs 50 extend through openings formed in a lifting ring 51 and opposite ends of the studs are provided with limiting pins 53 to secure the door 42 to ring 51. A pair of hinge members or ears 55 are secured at corresponding ends to lifting ring 51 and the other ends of the hinge members are provided with openings to receive a hinge pin 56 which is journalled in a hinge block 58 secured to frame 14.

A latch bar 60 is secured, as by welding, to lifting ring 51 and is provided adjacent the ring with an upstanding hand-gripping handle '61. Latch bar 60 has a depression 62 (FIG. 3) which is engaged by one end of a threaded clamping member 63, the threaded portion of said member cooperating with the threaded portion of a latch yoke 64. Latch 64 is substantially U-shaped and is adapted for pivotal movement on a pin 65 which extends through both arms of the yoke adjacent the lower portions thereof. The opposite ends of the pin 65 are mounted for rotation in bearing blocks 66 secured to frame 14.

Considering the structure thus far described, when air is injected through ports 32 and it is desired to displace door 42 to an open position, as shown in broken lines in FIG. 3, a finger-gripping portion 67 of clamping member 63 is rotated in the proper direction to elevate the lower end of said member out of recess 62 and above the upper surface of latch bar 60, as seen in FIG. 3. The operator then pivotally displaces yoke 64 to the broken line position shown in FIG. 3 and thereafter handle 61 is grasped to swing door 42 away from door frame 14.

As indicated hereinbefore, the fluid supplied to the access opening through the ports in the manifold is utilized to prevent escape of combustion gas known as flash-backs which is dangerous to operating personnel and such flash-backs occur in view of the greater pressure in the furnace as compared with that outside. In some arrangements of this general type, injury to personnel has occurred because of failure of the supply of fluid to the manifold, or clogging of the manifold ports to provide insufficient fluid to the access opening. The present invention provides means which prevent operation of the door unless a suflicient amount of fluid is flowing through. the manifold ports. To this end, a motion restraining member or locking pin 70 is adapted for sliding movement within a guide tube 72 securely mounted on a support bracket 73 fastened to frame 14. One end of locking pin 70 is adapted to enter an opening 75 (FIG. 1) in yoke 64 when the latter is in the full line position shown in FIGS. 1 to 3. The other end of locking pin 71 is positioned for engagement with one end of a piston rod 76 which projects outside of a fluid operated cylinder 77 secured to a bracket 78 by a threaded nut 79. A piston 86 is disposed in cylinder 77 and is biased by resilient means, as for example a spring 81, toward the locking pin 70. Cylinder 77 has a pair of inlets '82 and 83 disposed on either side of piston 80 and such inlets communicate with spaced points in conduit 38 by way of pressure lines 84 and 85, respectively. Disposed in conduit 38 between the last-mentioned points is orifice means 86 complising a disc 87 (FIG. 6) having an opening 88 therein. In actual manufacture, conduit 38 is separated in two portions, as shown in FIG. 6, at the point Where orifice disc 87 is located. The ends of separated portions of conduits 38 are threaded and cooperate with threaded unions 39 which in turn are brought together in tight relationship by a fitting ring 90. The direction of flow of fluid through conduit 38 is shown by the arrows in FIGS. and 6.

When flow of fluid exists in conduit 38 for delivery to manifold chamber 26 and through ports 32, the pressure of the fluid upstream of orifice means 86 is greater than the pressure of such fluid downstream of the orifice means. Such pressures are communicated to the opposite sides of piston 80 through lines 84 and 85 and the pressure of the fluid entering inlet 82 of cylinder 77 is sufficient to overcome the forces exerted by spring 81 and the pressure entering the cylinder through inlet 83. As a result, the projecting end of piston rod 76 is displaced in a direction away from locking pin 70. Conversely, when no flow of fluid to conduit 38 exists because of failure of supply to such conduit or in the event of clogging of ports 32, the pressures upstream and downstream of orifice means 36 are substantially equal. No differential pressure is reflected to cylinder 77, whereby piston 80 remains in the position shown in FIG. 2 with the projecting end of piston rod 76 engaging locking pin 70.

In operation, when the door 42 is in a closed position, as shown in FIGS. 1, 2 and 3, and an operator desires to displace door 42 to an open position for access to opening 30, a valve 91 (FIG. 5) in conduit 38 between orifice means 86 and a source of fluid, as for example air (not shown), is actuated to admit air through conduit 38. The air flows through orifice means 86 and through coupling 37 for entry into manifold chamber 26, where it is discharged for injection into access opening 29 through ports 32. At the same time, the pressure of the fluid upstream and downstream of orifice means 86 subject piston 80 to a differential pressure sufficient to overcome the bias of spring 81 in cylinder 77 to move piston 80 to the left (as shown in FIG. 3), thereby disengaging the projecting end of piston rod 76 from locking pin 70. Since the door assembly 12 is disposed in a vertical position, locking pin 70 is moved downwardly by air pressure differential and gravity to bring the upper end (as seen in FIG. 1) out of recess 75 in yoke 64. Yoke 64 is now unrestrained for movement to the broken line position shown in FIG. 3 and the operator rotates portion 67 of clamp 63 in the proper direction to elevate the lower end of the clamp above depression 62 in latch bar 60. Yoke 64 then is pivoted out of the path of movement of latch 60 whereby the operator may grasp handle 61 to swing door 42 outwardly and away from door frame 14. If it is assumed, in the foregoing description of operation, that an operator inadvertently neglects to actuate valve 9-1 to the proper position and/ or manifold ports 32 are clogged so that no fluid passes therethrough, the operator is unable to open door 4-2. The reasons for the inability of the operator to open door 42 is that no fluid flows through orifice means 86, whereby the pressures upstream and downstream of the latter are equal. Consequently, piston rod '7 6 is in engagement with locking pin 78 and the end of the latter remains in recess 75 of yoke 64. When the operator attempts to displace yoke 64 to the broken line position shown in FIG. 3, it will be discovered that locking pin 75 still engages yoke 64 and, therefore, the reasons for this condition will be brought to his attention.

In actual practice, it is assumed that if a certain number of ports 32 are clogged, as for example 25 percent, the amount of air injected by the latter will be insufficient to prevent flash-backs from occurring when door 42 is opened. Consequently, spring 81 in fluid operated cylinder 77 may be calibrated to provide a force suflicient to overcome the forces exerted by the pressure upstream of orifice means 86, if a number of ports 32 greater than 25 percent are clogged. In the claims that follow this description, the definition of the invention is not to be limited to conditions wherein only all of ports 32 are clogged but also to the number of clogged ports which provide less than the sufficient amount of fluid to prevent flash backs.

Although one embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the arrangement of parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

What is claimed is:

1. In combination with a pressurized vessel having a shell which defines an access opening in communication with the interior of the vessel, a door movable relative the shell between a closed position wherein the door is disposed in sealing engagement with the access opening and an open position wherein the door is spacially disposed relative the opening to permit entry into the vessel, latch means operatively arranged between the vessel and the door and movable between an engaged setting wherein it secures the door to the vessel in the closed position and a disengaged setting wherein it permits movement of the door between its open and closed positions, fluid injecting means for directing fluid under pressure into the vessel to form a fluid screen preventing escape of gas from the vessel through the opening, conduit means communicating the fluid injecting means with a supply of pressurized fluid, control means responsive to the rate of flow of fluid through the conduit means and connected to the latch means for maintaining the latch means in its engaged setting when the rate of flow of fluid is less than a set minimum rate, the control means comprising a flow obstruction connected in flow series with the conduit means between the supply of pressurized fluid and the fluid injecting means whereby the pressure drop across the flow obstruction is a direct function of the rate of flow of fluid through the conduit means, a motion restraining member comprising a movable element having a disengagement side and an engagement side and movable in response to a difference in pressures therebetween to move the latch means between its engaged and disengaged settings, a disengagement signal means communicating the disengagement side with the pressure of fluid in the conduit means u pstream of the flow obstruction, an engagement signal means communicating the engagement side with the pressure of fluid in the conduit means downstream of the flow obstruction so that the movable element registers the pressure drop occasioned by flow past the flow obstruction.

2. The combination set forth in claim 1 with the flow obstruction means comprising a restricted orifice.

3. In combination with a pressurized vessel having a shell which defines :an access opening in communication with the interior of the vessel, a door movable relative the shell between a closed position wherein the door is disposed in sealing engagement with the access opening and an open position wherein the door is spacially disposed relative the opening to permit entry into the vessel, a latch operatively arranged between the vessel and the door and movable between an engaged setting wherein it secures the door to the vessel in closed position and a disengaged setting wherein it permits movement of the door between its closed position and its open position, a manifold mounted about the access opening, the manifold defining a plurality of fluid injecting ports arranged to direct fluid under pressure into the vessel to form a fluid screen preventing escape of gas from the vessel through the opening, a conduit communicating the manifold with a supply of pressurized fluid, control means responsive to the rate of flow of fluid through the conduit and connected to the latch for maintaining the latch in its engaged setting when the rate of flow of fluid is less than a minimum rate, the control means comprising a flow obstruction connected in flow series with the conduit between the supply of pressurized fluid and the fluid injecting ports whereby the pressure drop across the flow obstruction is a direct function of the rate of flow of fluid through the conduit, a motion restraining member comprising a movable hydraulic element aligned to move the latch and having a disengagement side and an engagement side and movable in response to a difference in pressure therebetween, the movable hydraulic element connected to and aligned with the latch to move the latch between its engaged and disengaged settings, a disengagement signal means communicating the disengagement side with the pressure of fluid in the conduit upstream of the flow obstruction, an engagement signal means communicating the engagement side with the pressure of fluid in the conduit downstream of the flow obstruction so that the movable hydraulic element registers the pressure drop occasioned by flow past the flow obstruction, a resilient thrust element connected to the movable element and oriented to urge the latch into its engaged setting.

4. The combination set forth in claim 3 with the flow obstruction comprising a restricted orifice whereby when the fluid is passed through the orifice above a minimum rate the diiferential pressure across the movable hydraulic element overcomes the resilient thrust element to move the latch into its disengaged setting to permit movement of the door out of its closed position and whereby when flow through the conduit is below the minimum rate the resilient thrust element overcomes the pressure differential acting on the disengagement side of the movable hydraulic element to maintain the latch in its engaged position so that the door cannot be moved from its closed position.

5. The combination set forth in claim 4 with the motion restraining member comprising a piston housing, a piston openatively disposed in the housing, the piston coacting with the housing to define the disengagement side and the engagement side, a piston rod connected to the piston and penetrating out of the piston housing on the disengagement side to connect with the latch.

References Cited in the file of this patent UNITED STATES PATENTS 2,296,255 Bloom Sept. 27, 1942 2,545,886 Kooistra Mar. 20, 1951 2,775,216 Alexefi et a1. Dec. 25, 1956 2,823,629 Wittke Feb. 18, 1958 

